The use of chemically amplified resists for photomask manufacturing requires tight control of the post exposure bake (PEB) step, which completes the chemical reaction initiated by pattern exposure. Because the final pattern dimensions are influenced by the bake temperature and time, bake conditions must be kept uniform and repeatable to ensure that the CD uniformity of the exposure tool is faithfully transferred to the mask. Because the total thermal budget from the bake step strongly influences CD, the cross-plate matching of temperature ramp up and ramp down profiles is a key factor.

Sigmameltec’s SFB system addresses these challenges with an inherently uniform bake cavity optimized with peripheral thermal zones and fine-tuned with gas flow. The result is repeatable thermal exposure at every point on the mask, taking into account not only the steady state temperature uniformity but also the consistency of temperature-time profiles across the mask.

Key features and benefits:

Dual bake modules for increased throughput or to support two bake temperatures

Encapsulated bake environment with control zones for a highly uniform temperature map

Tightly matched ramp up and steady state temperature control for a consistent thermal budget across the mask